Quick exhaust valve

ABSTRACT

A valve for quickly exhausting a working chamber such as for a press clutch and brake actuator. A cylindrical body has a bore open to the chamber and leading to a transverse vent passage. A poppet is slidable in said body between a closed position separating the chamber from the vent, and an open position. An annular chamber is formed between the poppet and body, and a unidirectional annular seal on the poppet permits rapid filling of this chamber. A restricted passage is provided for exhausting the chamber. The valve is closed by the pressure differential across the valve sealing area, plus a spring, and is opened by pressure on said seal.

United States Patent Primary Examiner-M. Cary Nelson AssistantExaminer-Robert J. Miller AttorneyHarness, Dickey & Pierce ABSTRACT: Avalve for quickly exhausting a working chamber such as for a pressclutch and brake actuator. A cylindrical body has a bore open to thechamber and leading to a transverse vent passage. A poppet is slidablein said body between a closed position separating the chamber from thevent, and an open position. An annular chamber is formed between thepoppet and body, and a unidirectional annular seal on the poppet permitsrapid filling of this chamber. A restricted passage is provided forexhausting the chamber. The valve is closed by the pressure differentialacross the valve sealing area, plus a spring, and is opened by pressureon said seal.

uick EXHAUST VALVE BACKGROUND OF THE INVENTION 1. Field of the InventionThe invention relates to quick exhaust or dump valves, and particularlyto valves which will rapidly exhaust working chambers such asfor brakeand clutch actuators. These are used for example in connection withmechanical presses, where rapid cycling of the machine is often requiredfor high production work. Valves of this type are connected directly tothe actuator working chamber, and respond to a pressure drop in thischamber to vent the chamber so as to rapidly complete the exhaustportion of the cycle.

2. Description of the Prior Art An example of such a device is found inFIG. 3 of Warnock U.S. pat. No. 3,039,440, dated June 19, 1962. Thisdevice has a body with a bore connected to the working chamber and apoppet slidable within the body. A restricted passage leads through thispoppet to a valve opening chamber which, when pressure is built uptherein, will open the poppet valve in response to a drop in workingchamber pressure.

Because both filling and evacuation of the valve opening chamber isthrough this restricted passage, definite limitations are placed on thecycle time of this prior art valve. Furthermore, the known valve is oflimited sensitivity when moving to its exhaust or dumping position,because of the substantial pressure differential which holds the valveclosed.

SUMMARY OF THE INVENTION According to the invention, a valve body isprovided having a bore one end of which is open to the working chamber,and a transverse vent passage. A poppet is slidable in said bore andforms an annular chamber therewith. The poppet has a central bore and aannular end sealing area which engages a transverse seat to separate theworking chamber from the vent. Pressure in the annular chamber is usedto shift the valve to its open or dumping position. This pressure isbuilt up through a restricted passage connecting the poppet bore withthe annular chamber and a unidirectional seal carried by the poppetwhich permits rapid filling of the annular chamber. A spring ispreferably used to urge the valve to a closed position. As pressure inthe working chamber drops, the pressure in said annular chamber exertsforce on said unidirectional seal to open the valve and quickly exhaustthe working chamber. The mean diameter of the end sealing area on thepoppet is so chosen as to control the force needed to open the valve.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view inelevation of the invention, the valve being shown in its closed positionmounted in a working chamber wall;

FIG. 2 is an enlarged fragmentary cross-sectional view taken in the areamarked 2 of FIG. 1 and showing the valve sealing surface; and

FIG. 3 is a partially cross-sectioned view of the valve in its open ordumping position.

DESCRIPTION OF THE PREFERRED EMBODIMENT The valve is generally indicatedat 11 and comprises a valve body generally indicated at 12 and a poppetgenerally indicated at 13. Valve body 12 has a cylindrical portion 14mounted in the wall 15 of a chamber indicated partially at 16. Thischamber may be the actuating chamber of a brake and clutch mechanism(not shown) for a mechanical press, although the invention is notlimited to the use of valve 11 in this embodiment. Chamber 16 isalternately pressurized and evacuated by valve means indicatedschematically at 17. In applications such as a press brake and clutch,pressurizing of chamber 16 may actuate the clutch for a work operation,while evacuation of the chamber effects a declutching and braking step,It is desirable that the cycling of the clutch and brake operation berapid in order to increase the production rate.

Valve body 12 has an enlarged portion 18 outside chamber 16. A centralbore 19 is formed in body 12, this bore being open to chamber 16 andterminating at a wall 2]. A transverse vent passage 22 extends throughportion 18 of body 12, a clearance aperture 23 being provided in wall 21for poppet 13.

The poppet has a cylindrical main portion 24 and an enlarged head 25,the poppet being disposed within bore 19 and extending through aperture23 with head 25 being adjacent the open end of the bore. A helical coilcompression spring 26 is disposed within a counterbore portion 27 ofpoppet 13, the inner end of this spring resting against the shoulder 28on the poppet and the outer end being supported by a retainer 29. Thisretainer is held adjacent the open end of bore 19 by a snapring 31.

A bore 32 extends through poppet 13 from counterbore 27 to the outer endof the poppet. The diameter of poppet portion 24 is considerably lessthan that of bore 19 so that a chamber 33 is formed therebetween. Anannular seal 34 is disposed adjacent wall 21 and engages bore 19 andpoppet portion 24, thus constituting one end of chamber 33. The oppositeend of the chamber is formed by an annular unidirectional seal 35. Thisseal is shown as being a U-cup type of seal which is disposed betweenhead 25 of socket l3 and a shoulder 36 thereon. The outer diameter ofhead 25 is substantially less than the diameter of bore 19, and aplurality of circumferentially spaced notches 37 are formed in shoulder36. The arrangement is such that air may flow from chamber 16 into bore19, around seal 35 and into chamber 33, but seal 35 will resist flowfrom chamber 33 toward chamber 16. A restricted passage 38 is provided,however, between chamber 33 and working chamber 16. This constitutes aradial passage in poppet 13 which will permit controlled decompressionof chamber 33. Although seal 34 is shown as a U-shaped type of seal, itshould be understood that this seal need not be unidirectional in naturefor purposes of the invention.

The surface 39 of outer body wall 41 (FIG. 2) is flat and acts as a sealwhich the outer sealing surface 42 of poppet portion 24 engages when thevalve is closed. Although the area of seal surface 42 couldtheoretically be negligible, as a practical matter is necessary toprovide some area to prevent excessive wearing of the parts. As will bedescribed below, this area, and more particularly the location of itsmean diameter, furnishes a measure of the amount of force which holdpoppet 13 in its closed position and which, therefore, is needed to openthe valve. The strength of spring 26 need only be slightly greater thanthat necessary to overcome frictional drag of the parts. The area ofseal 35 against which pressure acts to open the valve should besubstantially greater than the closing forces.

In operation, let us assume that the parts are initially in their FIG. 1position but that chamber 16 is evacuated. At this point there will beno pressure in chamber 33 or in any other portions of the device. Uponapplication of pressure to chamber 16, air will flow into bore 19 ofbody 12 and bore 32 of poppet 13. Air will also rapidly fill chamber 33by passing around seal 35 and through restriction 38. Poppet 13 will beheld in its closed position as shown in FIGS. 1 and 2 by spring 26 andthe differential pressure area determined by the location of surface 42.

When evacuation of chamber 16 is initiated by valve 17, pressure will bereduced rapidly in bores 19 and 32. The pres sure in chamber 33 actingagainst seal 35 will, therefore overcome the force of spring 28 and thepressure differential force created by surface 42 and shift poppet 13 toits FIG. 3 position. This will rapidly dump the remaining pressure fromchamber 16. The pressure in chamber 33 will slowly be dissipated throughrestriction 38, at which time spring 28 will return poppet 13 to itsFIG. 1 position.

Should pressure be reapplied to a chamber 16 by valve 17 before thepressure in chamber 33 has been dissipated, poppet 13 will beimmediately returned to its closed position by virtue of the fact thatthe chamber 33 pressure is counteracted. It will be observed that thepresence of enlarged aperture 23 will tolerate misalignment of poppet 13during closing, and will also compensate for any distortion of body 12due to installation or mounting.

It should also be noted that the location of the mean diameter ofsealing surface 42 controls the net seating force of the poppet, thatis, the amount of force holding poppet l3 closed and, therefore, theforce necessary to open the poppet. Thus, for example, if it is desiredto open the poppet in response to a very slight pressure drop in chamber16, the mean diameter would be located in close proximity to the outsidediameter of main portion 24 of the poppet.

What is claimed is: I

1. In a quick exhaust valve, a valve body having a central bore open atone end to a working chamber to be alternately pressurized andevacuated, and a transverse vent passage at the opposite end of saidbody, a poppet slidable in said body between open and closed positions,said poppet having a head portion in said body and a cylindrical portionextending therefrom towards the transverse vent passage, a sealingsurface at said outer end of the poppet and a seating surface in saidbody which said sealing surface engages when the valve is closed, anannular chamber formed between said body bore and said cylindricalportion of the poppet, a seal between said cylindrical poppet portionand said body at the end of said chamber adjacent said vent passage, anannular unidirectional seal adjacent the head of said poppet and formingthe other end of said annular chamber, said last-mentioned sealpermitting flow only from the open end of said body bore towards saidchamber but preventing flow in the opposite direction, a bore extendingthrough said poppet, and a restricted passage between said annularchamber and said working chamber, whereby pressure applied to saidworking chamber will rapidly pressurize said annular chamber and saidworking chamber, whereby pressure applied to said working chamber willrapidly pressurize said annular chamber by means of said unidirectionalseal and will cause said poppet to move to its closed position by thepressure differential area created by the sealing surface of saidpoppet, reduction of pressure in said working chamber permitting thepressurized annular chamber to act against said unidirectional seal tothereby open said valve and dump the working chamber.

2. The combination according to claim 1, said restricted passagecomprising a radial passage in said cylindrical portion of the poppet.

3. The combination according to claim 1, said sealing surface of thepoppet comprising an area at the end of said cylindrical portionengaging a flat seating surface in said body, the mean diameter of saidarea being so located with respect to the outside diameter of thecylindrical portion of the poppet as to control the net seating force ofthe poppet.

4. The combination according to claim 1, said poppet head having asubstantially lesser diameter than said body bore.

5. The combination according to claim 1, further provided with a springurging said poppet in a closing direction.

6. The combination according to claim 5, said spring comprising ahelical coil compression spring having one end engageable with ashoulder on said poppet and the other end supported by a spring retainerin said body.

7. The combination according to claim 6, said poppet head having asubstantially lesser diameter than said body bore.

8. The combination according to claim 7, further provided with a springurging said poppet in a closing direction.

9. The combination according to claim 1, further provided with a wall insaid body between said chamber and said vent passage, said wall havingan enlarged clearance aperture for said poppet which will toleratemisalignment thereof.

10. The combination according to claim 9, said chamber seal adjacentsaid vent passage being supported by said wall.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 608,581 Dated September 28, 1971 Inve bi) Roger L. Sweet It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, line 43, 'hold" should be --holds-. Column 3, line 30, delete"and said working chamber"; line 31, delete entire line; and line 32,delete pressurize said annular chamber".

Signed and sealed this 18th day of April 1972.

(SEAL) Attest ROBERT GOTTSCHALK EDWARD M. FLETCHER JR Commissioner ofPatents Attezting Officer

1. In a quick exhaust valve, a valve body having a central bore open atone end to a working chamber to be alternately pressurized andevacuated, and a transverse vent passage at the opposite end of saidbody, a poppet slidable in said body between open and closed positions,said poppet having a head portion in said body and a cylindrical portionextending therefrom towards the transverse vent passage, a sealingsurface at said outer end of the poppet and a seating surface in saidbody which said sealing surface engages when the valve is closed, anannular chamber formed between said body bore and said cylindricalportion of the poppet, a seal between said cylindrical poppet portionand said body at the end of said chamber adjacent said vent passage, anannular unidirectional seal adjacent the head of said poppet and formingthe other end of said annular chamber, said last-mentioned sealpermitting flow only from the open end of said body bore towards saidchamber but preventing flow in the opposite direction, a bore extendingthrough said poppet, and a restricted passage between said annularchamber and said working chamber, whereby pressure applied to saidworking chamber will rapidly pressurize said annular chamber and saidworking chamber, whereby pressure applied to said working chamber willrapidly pressurize said annular chamber by means of said unidirectionalseal and will cause said poppet to move to its closed position by thepressure differential area created by the sealing surface of saidpoppet, reduction of pressure in said working chamber permitting thepressurized annular chamber to act against said unidirectional seal tothereby open said valve and dump the working chamber.
 2. The combinationaccording to claim 1, said restricted passage comprising a radialpassage in said cylindrical portion of the poppet.
 3. The combinationaccording to claim 1, said sealing surface of the poppet comprising anarea at the end of said cylindrical portion engaging a flat seatingsurface in said body, the mean diamEter of said area being so locatedwith respect to the outside diameter of the cylindrical portion of thepoppet as to control the net seating force of the poppet.
 4. Thecombination according to claim 1, said poppet head having asubstantially lesser diameter than said body bore.
 5. The combinationaccording to claim 1, further provided with a spring urging said poppetin a closing direction.
 6. The combination according to claim 5, saidspring comprising a helical coil compression spring having one endengageable with a shoulder on said poppet and the other end supported bya spring retainer in said body.
 7. The combination according to claim 6,said poppet head having a substantially lesser diameter than said bodybore.
 8. The combination according to claim 7, further provided with aspring urging said poppet in a closing direction.
 9. The combinationaccording to claim 1, further provided with a wall in said body betweensaid chamber and said vent passage, said wall having an enlargedclearance aperture for said poppet which will tolerate misalignmentthereof.
 10. The combination according to claim 9, said chamber sealadjacent said vent passage being supported by said wall.